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Science

Sea Levels Rising in Indian Ocean

A new study has detected rising sea levels in parts of the Indian Ocean, including the coastlines of the Bay of Bengal, the Arabian Sea, Sri Lanka, Sumatra and Java.

The study looked at data going back to the 1960s, combined with satellite observations, and found that the conclusions pointed towards anthropogenic climate warming as the likely cause behind the sea level rise threatening inhabitants of some coastal areas and islands.

“Our results from this study imply that if future anthropogenic warming effects in the Indo-Pacific warm pool dominate natural variability, mid-ocean islands such as the Mascarenhas Archipelago, coasts of Indonesia, Sumatra and the north Indian Ocean may experience significantly more sea level rise than the global average,” said Han of CU-Boulder’s atmospheric and oceanic sciences department.

The paper was published in the journal Nature Geoscience and looked at the effect that anthropogenic warming was having on two primary atmospheric wind patterns, the Hadley circulation and the Walker Circulation.

The Hadley circulation in the Indian Ocean is dominated by air currents rising above strongly heated tropical waters near the equator and flowing poleward, then sinking to the ocean in the subtropics and causing surface air to flow back toward the equator. The Indian Ocean’s Walker circulation causes air to rise and flow westward at upper levels, sink to the surface and then flow eastward back toward the Indo-Pacific warm pool.

“The combined enhancement of the Hadley and Walker circulation form a distinct surface wind pattern that drives specific sea level patterns,” said Han.

The main evidence that has led researchers to investigate this has been the heating of the Indo-Pacific warm pool which has heated by 0.5 degrees Celsius (1 degree Fahrenheit). The warm pool is a huge bathtub-shaped area of the tropical oceans stretching from the east coast of Africa west to the International Date Line in the Pacific.

“Our new results show that human-caused changes of atmospheric and oceanic circulation over the Indian Ocean region — which have not been studied previously — are the major cause for the regional variability of sea level change,” wrote the authors in Nature Geoscience.

Source: University of Colorado at Boulder




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